Maybe you've experienced Denver's world-class museums by day. But have you discovered what's happening after hours? Some of the city's greatest attractions host extremely fun nighttime events that will make you re-think what a museum can be. [Note: these are 21+ events]

UNTITLED FINAL FRIDAYS AT DENVER ART MUSEUM

WHEN: Final Friday of the month, January-October, 6–10 p.m.
WHERE: Denver Art Museum
COST: $10 for Colorado residents, $13 for non-residents, free for members, college students with valid ID receive 2-for-1 admission
Expect the unexpected at Denver Art Museum's Untitled events! These are witty, irreverent events, each one radically different from the last. Get an offbeat art fix, pick up a creative skill, take in an unexpected performance, and mix and mingle with local movers and makers. Top it off with a cash bar, munchies and a dose of pure whimsy and you've got an artful night out.

SCIENCE LOUNGE AT DENVER MUSEUM OF NATURE & SCIENCE

WHEN: Third Thursday of the month, 6:30-9:30 p.m.
WHERE: Denver Museum of Nature & Science
COST: $15 (non-member), $13 (member)
Nature and science meet cocktails and conversation at Denver Museum of Nature & Science's monthlyScience Lounge events. You might see a scientist jamming on a guitar, get a henna tattoo, drink local Colorado wine and meet some of the city's coolest people. And it's all in the name of science! Join the Science Lounge crowd for drinks, mind-expanding science and entertainment.

EVENINGS AL FRESCO AT DENVER BOTANIC GARDENS

WHEN: Monday–Thursday, June–August, 5–8 p.m.
WHERE: Denver Botanic Gardens
COST: $40 (non-members), $35 (members)
Head to the urban oasis that is Denver Botanic Gardens for Evenings al Fresco, a nighttime series of events taking place this summer at the Hive Garden Bistro at the York Street location. You'll celebrate the gardens with dinner specials like Burger Madness Mondays, Taco Tuesdays, Sprout Night at the Gardens on Wednesdays (kids get 50 percent off) and Hand-Tossed Pizza Madness. Plus, you'll get half off general admission tickets on Thursday evenings, June–August.

DENVER BOTANIC GARDENS SUMMER CONCERT SERIES

WHEN: June–AugustWHERE: Denver Botanic Gardens COST: Varies
In addition to Evenings al Fresco, Denver Botanic Gardens features a wildly popular Summer Concert Series. The lawns surrounding the stage are general admission, so bring a blanket or lawn chair along with a bottle of wine and a picnic dinner and enjoy the great music in an unparalleled setting. Word to the wise: Virtually all Botanic Gardens concerts sell out — so get your tickets early!

Rainforest Yoga at the Butterfly Pavilion

WHEN: Wednesdays, 5:30–6:30 p.m.
WHERE: Butterfly Pavilion
COST: $8 for members, $10for non-members
Stretch, breathe and relax in a rainforest in the middle of Colorado, surrounded by exotic plants and beautiful butterflies. Rainforest Yoga at the Butterfly Pavilion provides a fun and unique environment for unwinding and de-stressing.